Bulletin of the American Physical Society
APS March Meeting 2018
Volume 63, Number 1
Monday–Friday, March 5–9, 2018; Los Angeles, California
Session V26: Quantum Resource Theories IIFocus

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Sponsoring Units: DQI Chair: Eric Chitambar, Southern Illinois University Room: LACC 404A 
Thursday, March 8, 2018 2:30PM  3:06PM 
V26.00001: Resourcetheory models for thermodynamics Invited Speaker: Nicole Yunger Halpern The resourcetheory framework is a mathematical toolkit developed in quantum information theory. The framework models transformations—of quantum states or probability distributions—under restricted classes of operations. Thermodynamics constrains operations to conserve energy. An agent may access easily only states thermal relative to the ambient temperature. Athermal states can carry more information than thermal states do, more accessible energy, and/or more coherence relative to the energy eigenbasis. These properties serve as resources in thermodynamic tasks. For example, work may be extracted from a bath hotter than the environment, via a heat engine. Thermodynamic resource theories (TRTs) are used to quantify athermal states’ value. Quantification measures include "oneshot" entropies beyond the Shannon, von Neumann, and relative entropies. TRTs extend to quantum systems that exchange conserved charges, analogous to heat and particles, that fail to commute. This talk will overview TRTs. The framework stretches statistical mechanics beyond equilibrium, to small (e.g., threelevel) systems, to coherent quantum states, and to noncommuting charges. 
Thursday, March 8, 2018 3:06PM  3:18PM 
V26.00002: The Quantum Cohering Power of Local Channels Masaya Takahashi, Eric Chitambar The resource theory of quantum coherence studies coherence as a fundamental feature of quantum systems that can be converted from one form to another. Similar to the resource theory of entanglement, different measures of coherence have been proposed. The cohering power of a quantum channel can be defined, which is the maximum amount of coherence the channel can generate over all inputs. In this talk we show that the cohering power of certain channels can be increased when acting one half of an entangled state. In other words, the channel is able to generate more coherence on the joint system than on just the subsystem that it acts. 
Thursday, March 8, 2018 3:18PM  3:30PM 
V26.00003: Subadditity of logarithmic violation of geometrical Bell inequalities for qudits. Marcin Wiesniak, Palash Pandya Geometric inequalities for qubits [1] possess the highest robustness against the white noise among know correlationbased formulations. We present a construction of Bell inequalities for a collection of arbitrarily large subsystems (each with dimension d), with (d1)parameter family of local observables. The sum of outcomes of local measurments is represented as one of (d1)dimensional nonorthogonal vectors. We find the precise extimates of violation of the inequalities and observe that it grows exponentially with the number of (most probably) sublinearly with d. The intesting aspect is that we can compare the amount of nonclassiclity manifested in a single Bell experiment with subsystem that are composed of smaller parts with experiments conducted on these parts. The results of this comparison are counterintuitive. 
Thursday, March 8, 2018 3:30PM  4:06PM 
V26.00004: Local manipulation of multipartite entanglement Invited Speaker: Barbara Kraus Many applications of quantum information rely on the potentiality of quantum systems to be correlated. For pure states, these correlations coincide with entanglement. Hence, the qualification and quantification of multipartite entanglement is one of the central topics within quantum information. However, as the dimension of the Hilbert space grows exponential with the number of considered subsystems, many very fundamental questions in this context are still unanswered. 
Thursday, March 8, 2018 4:06PM  4:18PM 
V26.00005: Quantifying Genuine Multipartite Correlations and their Pattern Complexity Davide Girolami, Tommaso Tufarelli, Cristian E. Susa We propose an informationtheoretic framework to quantify multipartite correlations in classical and quantum systems, answering questions such as: what is the amount of sevenpartite correlations in a given state of ten particles? We identify measures of genuine multipartite correlations, i.e., statistical dependencies which cannot be ascribed to bipartite correlations, satisfying a set of desirable properties. Inspired by ideas developed in complexity science, we then introduce the concept of weaving to classify states which display different correlation patterns, but cannot be distinguished by correlation measures. The weaving of a state is defined as the weighted sum of correlations of every order. Weaving measures are good descriptors of the complexity of correlation structures in multipartite systems. Reference: Phys. Rev. Lett. 119, 140505 (2017). LAUR number LAUR1729988 
Thursday, March 8, 2018 4:18PM  4:30PM 
V26.00006: The Entanglement Hierarchy of 2 x m x n Systems Martin Hebenstreit, Mariami Gachechiladze, Otfried Gühne, Barbara Kraus We consider three partite pure states in the Hilbert space of dimensions 2,m,n and investigate to which states a given state can be locally transformed with a nonvanishing probability. Whenever the initial and final state are elements of the same Hilbert space, the problem is solved via the characterization of the SLOCC classes. However, when considering transformations from higher to lower dimensional Hilbert spaces, a hierarchy among the states can be found. We build on results presented in [1], where a connection to linear matrix pencils has been drawn in order to study SLOCC classes in 2,m,n systems. We first show that a generic set of states of dimensions 2,m,n, where n=m is the union of infinitely many SLOCC classes. However, for n≠m, there exists a single SLOCC class which is generic. Using this result, we derive a hierarchy of SLOCC classes for generic states. We also investigate common resource states, which are those states which can be transformed to any state (not excluding any zeromeasure set) in the smaller dimensional Hilbert space. 
Thursday, March 8, 2018 4:30PM  4:42PM 
V26.00007: Optimising the distribution of entanglement in quantum networks Kenneth Goodenough, Stephanie Wehner, David Elkouss Quantum communication is one of the most promising technologies enabled by quantum mechanics, providing the potential to perform a host of useful tasks, including quantum key distribution and coin tossing. The holy grail of quantum communication is the creation of a quantum network, where a collection of endusers can exchange quantum information over long distances. In particular, a quantum network should be able to generate entanglement between any arbitrary pair of endusers, with the ability to make a tradeoff between the generation time and the quality of the entanglement. That is, one would like to find a protocol that, for a fixed quality parameter, minimises the generation time. Here, we perform a restricted, numerical optimisation to find realistic protocols that can be implemented in a nearterm quantum network. By exploring the parameterspace, we improve on known protocols and discover general heuristics for the distillation of entanglement over quantum networks. 
Thursday, March 8, 2018 4:42PM  4:54PM 
V26.00008: Dynamics of Entanglement and the Schmidt Gap in a Driven LightMatter System Fernando GómezRuiz, Juan MendozaArenas, Ferney Rodriguez, Luis Quiroga, Neil Johnson The ability to modify lightmatter coupling in time (e.g. using external pulses) opens up the exciting possibility of generating and probing new aspects of quantum correlations in manybody lightmatter systems. In the present work we study the impact of such a pulsed coupling on the lightmatter entanglement in the Dicke model as well as the respective subsystem quantum dynamics. Our dynamical manybody analysis exploits the natural partition between the radiation and matter degrees of freedom, allowing us to explore timedependent intrasubsystem quantum correlations by means of squeezing parameters, and the intersubsystem Schmidt gap for different pulse duration (i.e. ramping velocity) regimes  from the near adiabatic to the sudden quench limits. Our results reveal that both types of quantities indicate the emergence of the superradiant phase when crossing the quantum critical point. In addition, at the end of the pulse light and matter remain entangled even though they become uncoupled, which could be exploited for engineering protocols to generate entangled states in noninteracting systems. 
Thursday, March 8, 2018 4:54PM  5:06PM 
V26.00009: Entanglement spectrum of engineered NMR spin Hamiltonians Kent Ueno, Krishan Canzius, Xuan Wei, Paola Cappellaro, Chandrasekhar Ramanathan Experimentally characterizing the complexity of manybody quantum dynamics in physical systems is a challenging task. A new correlation metric, similar to an outoftimeordered correlator (OTOC), was recently used to experimentally characterize the transition between a noninteracting, Anderson localized phase, and an interacting manybody localized phase in a model NMR system [1]. Here we use eigenvalue spectrum statistics (ESS) to study the properties of this class of experimentally accessible spin Hamiltonians that can be implemented in solidstate NMR experiments. ESS has recently gained attention for the ability to differentiate between different dynamical phases in simulations. We show that this model does indeed display a rich dynamical behavior, showing Poisson, Gaussian Orthogonal Ensemble (GOE), and Gaussian Unitary Ensemble (GUE) distributions in different experimentallyaccessible parameter regimes. These results can guide the design of NMR OTOC experiments to probe these dynamical transitions. 
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